The present invention relates in general to headlamps for a motor vehicle and, more particularly, to an improved lamp-within-a-lamp headlamp design having an inner seal between an inner lamp body and an outer headlamp housing.
Headlamps for motor vehicles have evolved from sealed beam systems wherein self-contained headlamp units each include one or two filaments, a reflector and a lens, all of which are formed into a glass shell with terminals extending out the back of the unit for electrical connections to the filament or filaments. Such sealed headlamp units are mounted into support frames which are adjusted typically from the front of the vehicle to properly align or aim the light beams projected from the vehicle.
To simplify headlight installation in a vehicle, adjustment of headlamp alignment and replacement of burned-out headlamp filaments, headlamp units have been designed which are adjustably supported within a vehicle for receiving a headlamp bulb, typically a halogen bulb, from the rear of the unit. Such improved headlamp units eliminate substantial amounts of waste when headlamp filaments burn out and must be replaced. Headlamp alignment or aiming is simplified and typically performed from the rear of the headlamp unit. Exemplary headlamp units of this form are disclosed in U.S. Pat. No. 4,471,413 and No. 4,569,007.
Another form of improved headlamp unit is disclosed, for example, in U.S. Pat. No. 4,574,334. This form of headlamp unit includes a lamp-within-a-lamp, i.e. a reflector which supports a bulb is adjustably supported within a lamp housing. As is apparent from this patent, the inner lamp or reflector is supported near the ends of adjustment screws, pivot members and the like such that it is subject to being deflected due to forces produced as the vehicle including the headlamp unit is driven. Further, the lamp housing is sealed such that dirt and moisture cannot accumulate on the lens which is on the front of the reflector. Since the lamp housing is sealed, all alignment adjusters must also be sealed where they enter the housing or else the housing seal will be compromised. The added complexity required by sealing the alignment adjusters is also apparent from a review of this patent.